JPH0646684B2 - Pseudo waveform generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pseudo waveform generating circuit that generates a pseudo waveform such as a pseudo sin wave or a pseudo con wave by a monotonically increasing or decreasing input.

[Conventional technology]

Conventionally, the pseudo waveform generating circuit, as shown in FIG. 3, the resistance of the reference voltage V _{reg R 1,} R _2, R _3, R 4, by dividing by the voltage dividing circuit consisting of _{R 5,} the resistors R ₁ ~
Obtaining voltages V ₁ , V ₂ , V ₃ , and V ₄ from the connection point of R ₅ ,
Each of the voltages V _{1 to} V ₄ and the input voltage V _IN that monotonically increases and decreases are compared by the comparators C ₁ , C ₂ , C ₃ and C ₄ , and the pseudo waveform shown in FIG. 4 is obtained.

[Problems to be solved by the invention]

In such a pseudo waveform generating circuit, the accuracy of the pseudo waveform depends on the voltages V _{1 to} V ₄ , the accuracy of the resistance ratio of the resistors R _{1 to} R ₅ affects the waveform accuracy, the number of resistors is large, and the resistance ratio is set. However, there is a drawback that the waveform accuracy is low such that the temperature characteristics of the resistors R _{1 to} R ₅ directly appear in the pseudo waveform output.

Therefore, the present invention avoids the inconvenience of forming the waveform component based on the voltage division by the resistance ratio, and improves the waveform accuracy.

[Means for solving problems]

The pseudo waveform generating circuit of the present invention, as illustrated in FIG. 1, is a first triangular wave generating means for generating _a triangular wave (triangular wave voltage V _a ) according to an input (input voltage V _in ) that monotonically increases or decreases. (2A), second triangular wave generating means (2B) for generating a pair of triangular waves (triangular wave voltage V _b ) corresponding to the triangular wave generated by the first triangular wave generating means as an input, and the second triangular wave generating means (2B). By receiving the triangular wave generated by the triangular wave generating means, generating a trapezoidal wave together with the triangular wave corresponding to the triangular wave, and adding the triangular wave and the trapezoidal wave, a waveform output (voltage V
_And a waveform shaping means (waveform generating circuit 4) for generating _OUT .

[Action]

According to this structure, the triangular wave output (triangular wave voltage V _a ) obtained by the first triangular wave generating means (triangular wave generating circuit 2A) is input to the second triangular wave generating means (triangular wave generating circuit 2B) to input the triangular wave. To obtain a pair of continuous triangular wave outputs (triangular wave voltage V _b ).

Then, this triangular wave output is added to the waveform shaping means (waveform shaping circuit 4), and together with the triangular wave corresponding to this triangular wave,
By generating a trapezoidal wave and adding the triangular wave and the trapezoidal wave, a waveform output representing a pseudo sin wave or a pseudo cos wave can be obtained.

〔Example〕

FIG. 1 shows an embodiment of the pseudo waveform generating circuit of the present invention.

This pseudo-waveform generation circuit uses sin
A waveform shaping circuit 4 for approximating a regular waveform by waveform shaping together with the triangular wave generating circuits 2A and 2B as first and second triangular wave generating means in order to obtain a waveform output representing a pseudo waveform such as a wave or a cos wave. Are connected in series.

The triangular wave generating circuit 2A on the upstream side constitutes a first triangular wave generating means for generating a single triangular wave output in response to a monotonically increasing or decreasing input, and the monotonically increasing or decreasing input is the variable voltage source 3 Set by. That is, the second
Input terminal 6 from the voltage V _in is a variable voltage source 3 shown in A of FIG,
8 through all feedback amplifiers (hereinafter referred to as amplifiers) 10
Entered in. The amplifier 10, the voltage source 12 by the upper reference voltage V _refH, is set with a lower limit reference voltage V _refL by the voltage source 14, the input voltage V _in from the variable voltage source 3, the lower limit reference voltage V _refL and upper It monotonically increases or decreases with the reference voltage V _refH .

The output point of the amplifier 10 has a common voltage _dividing point of the resistors 16 and 18 connected between the upper limit reference voltage V _refH and the lower limit reference voltage V _refL . In this case, the input voltage V _in and the midpoint voltage V _r become equal due to the total feedback characteristic of the amplifier 10, and the resistance values of the resistors 16 and 18 are set to R ₁₆ and R ₁₈ , and when both are set to the same value, the amplifier 10 is set. If the outputs of are not connected, the midpoint voltage V _r ′ is Becomes

Then, the first current mirror circuit 20 compensates the current I ₁ flowing out from the amplifier 10 through the resistor 18 with respect to the amplifier 10, and reverses the current I ₁ to generate a second current I ₁ .
The current mirror circuit 22 supplies the current I ₂ absorbed by the amplifier 10 through the resistor 16 out of the amplifier 10 and outputs the current I ₁ or the current I ₂ to the output resistor. 24

Thus, the first triangular wave generating circuit 2A, also increases or decreases the midpoint voltage V _r in response to an increase or a decrease of the input voltage V _in, also increases or decreases the voltage between the terminals V _R of the resistor 18 in accordance with the increase or decrease. For example, when the input voltage V _in increases above the midpoint voltage V _r ′, the current I ₁ flows out from the output point of the amplifier 10, and the current I ₁ is generated.
Are supplied from the current mirror circuit 20 to the amplifier 10. The current I ₁ supplied to the amplifier 10 flows from the current mirror circuit 20 into the current mirror circuit 22 by the current mirror effect, flows through the current mirror circuit 22 into the output resistor 24, and causes a voltage drop.

Further, when the input voltage V _in decreases below the midpoint voltage V _r ′,
Since the midpoint voltage V _r decreases and the voltage V _R across the resistor 18 also decreases, the current I ₂ coming from the resistor 16 is drawn into the amplifier 10. The current I ₂ absorbed by the amplifier 10 flows into the current mirror circuit 22 from the amplifier 10 and the current I ₂
Is absorbed by the current mirror circuit 22 through the output resistor 24 due to the current mirror effect. As a result, a voltage drop occurs in the output resistance 24 due to the current I ₂ .

From such input-output relation, the output to the low-potential side output point of the resistors 24, as shown in B of FIG. 2, _'left and right around the target midpoint voltage V _r' midpoint voltage V _r of The first triangular wave voltage V _a having a constant increasing / decreasing relationship with the point as the maximum value is obtained. The triangular wave voltage V _a is a triangular wave generating circuit 2 of the next side
B is applied as an input voltage.

The triangular wave generating circuit 2B is composed of the same circuit as the triangular wave generating circuit 2A, and from the similar current relation, C of FIG.
As shown in FIG. 2, a pair of triangular wave voltages V _b that are individually continuous are formed by the increasing component on the left side and the decreasing component on the right side of the triangular wave voltage V _a shown in B of FIG. This triangular wave voltage V
_b, the lower limit reference voltage V _refH voltage _{V r} ', the two pairs of triangular wave having the upper limit reference voltage V _refH voltage _{V r} ".

The triangular wave voltage V _b composed of such two sets of triangular waves is applied to the waveform shaping circuit 4 that shapes the waveform components having a monotonous increase / decrease relationship of the triangular waves into waveform components having different slopes.

The waveform shaping circuit 4 is for making the waveform shape of the triangular wave of the triangular wave voltage Vb close to a trigonometric function waveform to form a pseudo waveform representing a sin wave. For example, the triangular wave and the trapezoidal wave are combined in response to the triangular wave input. Then, a pseudo waveform of trigonometric function is formed. For this reason, the waveform shaping circuit 4 is provided with voltage / current conversion circuits 41 and 42 as two current generating means, and the triangular wave voltage V _b is applied to each voltage / current conversion circuit 4.
It is converted into currents I ₃ and I ₄ by 1, 42.

The voltage / current conversion circuit 41 is composed of an amplifier 44, a transistor 46 and a resistor 48.
Assuming that the resistance value of the resistor 48 is R ₄₈ according to the total feedback characteristic of, the current I ₃ is And becomes a value that increases or decreases in proportion to the input.

Further, the voltage / current conversion circuit 42 includes a comparison circuit 50, and compares the reference voltage V _refH and the reference voltage V _refL with the resistor 5.
The reference voltage V _t is set by dividing the value into 2 and 54. In the voltage-current conversion circuit 42, to the extent that component voltage of the triangular wave voltage Vb does not exceed the reference voltage V _t, has a proportional relationship to the component voltage, exceeds the reference voltage V _t, the trapezoidal becomes constant value Generate a current I ₄ . That is, the comparison circuit 5
As for 0, an all-feedback amplifier is constituted by the transistor 56 and the resistor 58, and assuming that the resistance value of the resistor 58 is R ₅₈ , the current I ₄ is Next, until the triangular wave voltage V _b is moved to the reference voltage V _t, a value proportional to the component voltage of the triangular wave voltage V _b.

The respective currents I ₃ and I ₄ are added on the line on the input side of the current mirror circuit 60 as the current conversion means, and the combined current I _T
(= I ₃ + I ₄ ) is added to the current mirror circuit 60. This current mirror circuit 60 has a resistor 6 as a voltage converting means connected to its output side by the current mirror effect.
A combined current I _{T is} passed through 2. Therefore, assuming that the resistance value of the resistor 62 is R ₆₂ , the voltage V generated in the resistor 62 is
_OUT is V _OUT = R ₆₂ · _IT = R ₆₂ · (I ₃ + I ₄ ) ... (4)

If the resistance ratio of the resistance values R ₄₈ , R ₅₈ , and R ₆₂ is R ₄₈ : R ₅₈ : R ₆₂ = 1: 1: 1,
Voltage drop _R 62 · _{I 3} due to the current _{I 3} is equal to the triangular wave voltage Vb shown in C of FIG. 2, also, the voltage drop across _R 62 · _{I 4} due to current _{I 4} is trapezoidal wave shown in D of FIG. 2 Voltage V
_c .

The respective voltages V _b and V _c are combined to form a voltage drop in the resistor 6
2 occurs, the voltage V _OUT represents a pseudo sin wave composed of a combined value of the voltages V _b and V _c as shown in E of FIG. 2, and the pseudo waveform corresponding to the input voltage V _in from the output terminal 64. Taken as output.

Then, in the waveform shaping circuit 4, the values R ₄₈ , R ₅₈ , and R of the resistors ₄₈ , ₅₈ , and 62 are set based on the input / output relationship.
_A desired waveform shape can be set by arbitrarily setting ₆₂ .

In addition, this pseudo waveform voltage V obtained from the output terminal 64
_OUT is made into a condensed sin wave for one cycle by inverting a half cycle through the waveform inverting means, and as a pseudo cos wave by displacing the waveform by a quarter cycle on the time axis. You can take it out.

〔The invention's effect〕

According to the present invention, after a triangular wave is obtained from an input that monotonically increases or decreases, a pair of continuous triangular waves is obtained from the triangular wave, and the slope is converted in the middle of the waveform component corresponding to the triangular wave. , A sine wave or a cos wave can be easily obtained, and since the waveform component does not depend on the resistance ratio when using a resistance circuit connected in series continuously as in the past, the temperature of the resistance A highly accurate waveform output can be obtained without depending on the coefficient or the resistance ratio accuracy due to the continuous resistance thereof.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a pseudo waveform generating circuit of the present invention, FIG. 2 is a diagram showing the operation of the pseudo waveform generating circuit shown in FIG. 1, and FIG. 3 is a conventional pseudo waveform generating circuit. The circuit diagram shown in FIG. 4 is a diagram showing formation of a pseudo waveform by the pseudo waveform generating circuit shown in FIG. 2A ... Triangle wave generating circuit (first triangle wave generating means) 2B ... Triangle wave generating circuit (second triangle wave generating means) 4 ... Waveform shaping circuit (waveform shaping means)

Claims (1)

[Claims] 1. A first triangular wave generating means for generating a triangular wave in response to a monotonically increasing or decreasing input, and a pair of triangular waves corresponding to the triangular wave generated by the first triangular wave generating means as an input. By receiving the second triangular wave generating means and the triangular wave generated by the second triangular wave generating means, a trapezoidal wave is generated together with the triangular wave corresponding to the triangular wave, and the triangular wave and the trapezoidal wave are added. , A pseudo waveform generating circuit comprising: a waveform shaping means for generating a waveform output representing a pseudo trigonometric function.